
AND 


UTILIZING CONVERTER FLAME 


FOR 


HEATING CUPOLA BLAST. 



/2 3v2- H 


Note.— This Report is printed, not as a publication, 
but simply for the convenience of my clients, and for 
their exclusive use. 

A. L. HOLLEY. 



New York, October, 1877. 





\ 


Copyright. 

A. L. HOLLEY. 
1877. 





HEATING CUPOLA BLAST. 


The chief advantages of the hot-blast for cupola furnaces 
are: 

1st. A notable economy in fuel. 

2d. The longer and /nore uniform working of the furnace, 
due to the prevention of scaffolding, especially around the 
tuyeres. 

It has long been supposed that the hot-blast would prove as 
useful in cupola practice as in blast-furnace practice; and al¬ 
though the few experiments in this direction have substanti¬ 
ated the supposition, no attempt has until recently been made 
to adapt the hot-blast stove to regular cupola work. 

Heating the blast by the waste gases of the cupola itself has 
long been the subject of experiment, and for above a year, of 
regular practice, by Mr. Alexander AVilson at the Dronfield 
Bessemer Works near Sheffield. 

Utilizing the flame of the Bessemer vessel to heat the cupola 
blast had been brought to the stage of preliminary drawings 
last winter by Mr. Arthur Cooper (Bessemer manager) and 
Mr. C. B. Holland (General Manager), of Messrs. Brown, 
Bayley & Dixon’s Works in Sheffield. It has now been about 
two months in regular and very successful working at this 
establishment. 

I have postponed giving my clients the data 1 had about 
AVilson’s cupola until I could also get that about Coopers im- 



4 


provement, so as to present the two together. The accompa¬ 
nying engravings illustrate both arrangements, and I also have 
detailed working drawings. 

The improvement of Bessemer cupola practice assumes still 
greater interest now that the direct use of blast-furnace metal' 
is as vet hardly making good its early promises. In general 
foundry practice, the utilization of waste heat in this manner 
is, of course, a matter of great importance. 


Wilson’s iiot-blast cupola. 

The engraving so well illustrates the arrangement that little 
description is required. The stove is simply a series of hol¬ 
low rings, one above the other, connected on one side and on 
the other alternately, so that the blast will zig-zag as it comes 
down through them to the belly pipe. The alternate rings 
are of different diameters, so as to facilitate the impingement 
of the heating gases against them. The stove is set in the 
cupola stack. In small cupolas, such as those for spiegel, this 
stack is enlarged so as to give room for the stove. The cupola 
gases pass through and around the hollow rings. The thick 
brick lining of the chamber absorbs heat when the cupola is 
working hot above, and gives it off to the stove when less gas 
is burning. 

Upon looking into a cupola charging-door just after charg¬ 
ing, there does not appear to be flame enough to heat the 
blast materially, and when the charges are well burned down 
the heat seems sufficient to destroy a hot-blast stove. But 
the distillation of carbonic oxide must of course be pretty uni¬ 
form ; when cold materials are thrown on, its combustion is 
checked, but the gas is coming up just the same. The ar¬ 
rangement Mr. Wilson’s experiments have led him to, effectu¬ 
ally prevent both the above-mentioned difficulties. Bv the 
simple means of a wide fire-brick ledge running around the 
furnace a short distance above the charging-door, he shields 
the stove from the direct impact of the flame, and lie also 
forms a combustiun-chamber surrounded bv hot brick walls, 
in which the gases, upon being properly mixed with air, will 


5 


burn, or rather in which they will always be lighted , so that 
their combustion can go on continuously in the chamber above. 

In order that too much air shall not enter when the charg¬ 
ing-door is open, the throat leading from the combustion- 
chamber to the stove is contracted—not so much that the 
gases tend to puff out of the door, but so that a great volume of 
air shall not be drawn in. Suitable air-holes are made in the 
chamber, so that the combustion shall occur below the stove 
rather than at the chimney-top, as it does when insufficient 
air is admitted : and so that combustion shall be complete 
rather than partial and variable, as when a great volume of 
air rushes in. The air supply may be more perfectly con¬ 
trolled by steam-induced jets. The ledge and also the stove 
are sustained by wrought-iron brackets imbedded in the lining, 
and suitable passages conduct a part of the hot gases through 
the ledge and around the stove. 

It will also be observed that the chamber in which the stove 
is situated is narrowed at the top, so as to prevent the exit of 
the gases until they have given off their available heat. The 
blast enters the top of the stove where the gases are 
coolest, although its direction can be readily reversed, as in 
Mr. Edward Cooper’s hot-blast stoves at Durham, Pa., so as 
to secure greater endurance of pipes at some sacrifice of heat. 

The diameter of the blast-pipe and of the smallest air- 
passage in the stove is usually 15 in. for a 6 ft. (inside) cupola, 
but if fan-blast is used the passages should be larger. The 
bell-mouth joint between the pipes has I wedges and a luting 
of half iron-borings and half fire-clay. The rings are held 
apart by the joints and by cast-iron distance-pieces. There 
is, of course, an expansion-joint in the cold-air pipe and a 
slotted hole in the cupola-shell where it enters. 

The following are the principal dimensions, etc., of the 
cupolas and stoves, working at Wilson, Cammed & Co.’s, Dron- 
ffeld : 

MAIN CUPOLAS. 

Ft. in. 


Height, tap-hole to charging-door. 15 0 

“ “ lower tuyeres. 3 10 

“ “ upper tuyeres. 5 4 

“ charging-door to top of chimney. 21 0 






6 


Diameter, shell of furnace. 

body “ inside. 

‘ ‘ bosh “ * ‘ . 

No. tuyeres, upper row. 6 

Dia. “ “ . 

No. tuyeres, lower row. 6 

Dia. “ “ . 

No. rings in stove . 8 

Dia., larger do., over all. 

Dia., smaller do., “ . 

Dia. air-passage in rings. 

Thickness bottom rings. 

“ top “ . 


Weight of 8 rings. 9 tons. 

Heating surface do.336 sq. ft. 

Cost of apparatus (about).$1,000. 


Ft. in. 

7 6 
6 0 

3 9 

0 2j 
0 5 

5 3 

4 5 
1 3 
0 li 
0 Of 


SPIEGEL CUPOLA. 

No. rings.10 

Dia. larger rings, over all. 

“ smaller “ “ . 

4 ‘ air-passage in rings. 


3 9 
3 3 

0 9 


Performance .—The temperature of blast coming from a 
stove with 8 pipes varies from 550° to 600° F., as constantly 
measured by a pyrometer, and does not vary beyond these 
limits. A 6-pipe stove heats the air to about 400°. The 
best number of pipes has not been fully determined. A blue 
flame at the chimney-top, in the night, would of course 
indicate that the gas is not completely burned, and that the 
stove may be enlarged. 

The cupola fuel used at Dronfield before the application of 
the hot-blast was 1 lb. of coke to 7.2 lbs. of iron melted. 
Since the 8-ring stove was started, it lias been 1 lb. of coke 
to 12.4 lbs. of iron, which is a saving o i nearly forty-two per 
cent, of fuel. 

The melting capacity of the cupola has also been increased 
nearly twenty per cent. 

The charging is as follows : 3 tons of pig and 4^ cwt. of 
coke, 30 times per 12 hours, yielding 90 tons per turn. 

One of these stoves had been running some.seven months 
in March last, when I saw it, and it appeared to be as good 
as new. I am informed that it has since required no repairs. 






















I 


7 

Six of the stoves are working at Dronfield, and I learn that 
the improvement has been adopted at the Penistone and other 
Bessemer works, and in a number of foundries. 

This arrangement seems admirably adapted to the purpose. 
It is cheap, simple, compact and durable ; the stove ilia}’' be 
hoisted out of the top of the stack, and quickly replaced; the 
facilities for combustion are good; the opportunity for circu¬ 
lation of gases around the stove is ample, and the area for the 
blast may be made indefinitely large. These advantages are 
capable of accounting for the high economy and durability 
■which are realized. 

To apply the apparatus, no change in the cupola proper is 
needed, and no room is required other than that, or about 
that, which the ordinary stack occupies. But, simple as the 
arrangement appears, it has, like other simple and effective 
appliances, required much contrivance and experimenting. 

It has been suggested that, by simply raising the cupola, 
the waste carbonic oxide would be utilized in heating the 
stock, and so preparing it for more rapid melting, and that 
thus the cost of air-heating apparatus would be saved. The 
trouble is, however, that the waste gas will not heat the stock, 
nor anything else, until it is set on fire. To do this by 
injecting blast much above the main tuyeres would be (as has 
been proved by experiment) to make another melting zone, 
and to stop the free and continuous working of the furnace. 
Making Bessemer cupolas 5 or 6 feet higher, as will be 
shown further on, is economical; for a good deal of gas is 
burned to waste in our present low furnaces; but the only 
way to completely utilize the gas in a m^my-furnace, the 
conditions of which are entirely different from those of a 
smelting-furnace, is to burn it above the charges, and apply 
its heat outside of the furnace proper. 

cooper’s blast-iieating by waste vessel flame. 

The engraving of this apparatus fully illustrates its applica¬ 
tion to two adjacent vessels as arranged in English works. 
The same arrangement, substantially, may be readily applied 
to the American plant. 


8 


It is simply a pipe-stove placed in a brick chamber in such 
manner that while the vessel-flame need not impinge directly 
upon the pipes, the hot products of the flame come in contact 
with them and give up their heat to them. The air for the 
cupolas is passed through the stove. 

The flame from vessel A diffuses itself in stack C (Figs. 1 
and 2), which is covered and closed as a damper, I; the hot 
gases must thence pass into the pipe-chambers or stove, D, E, 
and F (Fig. 2), and finally into the stack, G, and off through 
the damper, H. When vessel B is at work the direction of 
the gas is reversed, the stove being common to both. 

The thick brick walls of the stacks and stove form a sort of 
regenerative chamber, and, both dampers being nearly closed, 
give off much heat to the pipes when neither vessel is blowing. 
When no air is passing through the stove, the damper over the 
vessel in use is opened, so as to prevent burning the pipes. 

It will be observed that, without necessarily following this 
exact plan, a large stove may be placed common to the two 
vessels, in such a way that flame will not play directly against 
the pipes, but so that a volume of highly-heated gas, larger 
than the volume of air delivered by the blowing-engine, will 
give up its heat to the pipes : and also that while the vessels 
are not blowing, a draft of hot air will surround the pipes. In 
other words, a stove arranged in this way —the value of Mr. 
Cooper’s invention lies in the arrangement —may be made at 
once durable and effective. It has heretofore been thought 
that vessel-heat was too fitful to be utilized, but the results to 
be mentioned prove quite the reverse. 

At Brown, Bayley & Dixon’s works, in Sheffield, this appa¬ 
ratus has been in use since the middle of August last. There 
is a blow once an hour from one vessel or the other. During 
the blow the cupola blast is heated to 500° F., and just before 
the next blow it has fallen to 400°. This fall of temperature 
would hardly occur at all in American works, where the blow¬ 


ing is almost continuous. 


I have appended the official record of the four weeks com¬ 
parative performance of hot and cold blast cupolas, just as I 
received it. 


0 


“ Pig iron melted and coke consumed during the four weeks 
ending September 22, 1877, in Bessemer B with ordinary 
cold-blast , and in Bessemer A with blast heated, by appa- 
tus recently constructed between No. 2 vessel , Bessemer 
A, and No. 1 vessel. Bessemer B. 


BESSEMER B CUPOLAS, 


COLD BLAST. 



Total Pig Iron Melted. 

Total Coke Consumed. 

Coke per ton of 
Pig Iron. 

Weeks ending 

Tons. 

c. 


Tons. 

c. 


cwts. 

1st September 

813 

4 

• . 

93 

, , 

1 

2.287 

1 8th 

829 

12 

, . 

82 

16 


1.996 

15th “ 

915 

8 


83 

14 

% # 

1.830 

2 2d 

883 

10 


84 

18 

3 

1.930 

Total . . 

3441 

14 


344 

9 

• • 

2.000 


BESSEMER A CUPOLAS, HOT BLAST. 



Total Pig Iron Melted. 

Total Coke Consumed. 

Coke per ton of 
Pig Iron. 

Weeks ending 

Tons. 

c. 


Tons. 

c. 


cwts. 

1st September 

924 

• • 

• • 

69 

13 


1.507 

8th 

852 

8 

• • 

63 

5 

2 

1.551 

15th 

1014 

10 

a . 

70 

13 

2 

1.391 

22d 

977 

10 


77 

5 

1 

1.580 

Total . . 

3768 

8 


280 

17 

1 

1.490 


“ Therefore the saving effected in coke by the use of hot- 
blast during the above four weeks , ending September 22, 1877, 
has been as follows: 2.00 cwts. less lAS-cwts. = .51 cwts. of 
coke per ton of pig iron melted ; 3,768 tons of pig iron at .51 
cwts. coke per ton — 96 tons of coke; 96 tons of coke at 
19s. — £91. This is at the rate of £1,137 per shop per an - 


num . 




























































10 


Within a few days I have received the following results : 

Week Ending Sept. 29, 1877.—837 tons of pig iron have been melted 
with 63£. 2c. 0 qrs. of coke, or lc. 2 qrs Of lbs. coke per ton of pig iron. 

Five Weeks Ending Sept. 29, 1877.—4,605.4 tons of pig iron have 
been melted with 343£. 19c. 1 qrs. of coke, or lc. 1 qrs. 27{lbs. coke per ton 
of pig iron. 

The following is a brief analysis of the results given in the 
tables: 


COLD BLAST. 


Lbs. iron melted with lib coal. 10 

HOT BLAST. 

Lbs. iron melted with lib. coal. 13.4 

Saving of coal by means of hot blast. 34$ 


This saving is not quite as large as that made at the Dron- 
field works, but it must be remembered that the latter started 
with an inferior practice, viz., 7.2 to 1, upon which it was easier 
to improve ; and that Brown, Bayley & Dixon have reached 
a higher economy, viz., 13.4 to 1 against 12.4 to 1 at Dron- 
field. 

The old practice at Brown, Bayley & Dixon’s was, before 
the application of the hot blast at either place, superior to that 
at Dronlield and elsewhere in England, for the following 
reasons: The cupolas had been raised from 14 to 21 feet in 
height. The hearth is 5 ft. in diameter and 5 ft. deep from 
the lower tuyeres (3 five-inch tuyeres) ; the upper tuyeres, 
of the same size, are 15 in. higher, and the diameter of furnace 
is narrowed at this point to 4)4 ft. The blast is ^ lb. 

The cupola lining is stone, and will stand melting about 
600 tons in the weakest place. 

I am further informed regarding Brown, Bayley & Dixorfs 
practice, 1st, that with the hot-blast “the tuyeres are always 
bright, and there is no scaffolding above them ” ; 2d, that 
“ the apparatus is in as perfect working order as it was on the 
day it started ”; 3d, that there is yet no brick-lined main 
from the stove to the cupolas, and that much heat is thus 
wasted; and, 4th, that at a late meeting of the directors it 





was determined to erect a brick-lined main, and to at once ap¬ 
ply the apparatus to all the other vessels. 

Conclusion. —Here are two methods of treating cupola 
blast by waste heat; they both give about the same economy, 
and it is a very substantial economy. The apparatus in both 
cases is simple, durable, and not expensive. That one or the 
other should be adopted generally in American works is too 
evident to require discussion. May not the two be united ? 
A pyrometer in the vessel stack at Brown, Bayley & Dixon’s 
showed the average general temperature to be 1,200° F., and 
the maximum to be 1,400°, which is probably much higher 
than that in the cupola stack. If this vessel-heat were stored 
and equalized by a mass of tire-brick—possibly heavy checker- 
work—surrounding the pipe-stove, it might add some hun¬ 
dreds of degrees to the temperature of the blast after it had 
left the cupola stove. 

It has certainly been proved that a very large amount of 
heat from the vessel-flame mav be saved and utilized, without 
danger to the apparatus, by means of the arrangement 
worked out by Mr. Cooper. Applying this heat to feed-water 
would evidently not be impracticable. 




I 

















































































































































